Sound signal



March 1, 1932. w. w. RIEDEL souu'n SIGNAL Filed March 19, 1928 ,m vk/ 14a My Patented Mar. 1, 1932 UNlTED STATESPATENT OFFICE 'WALTER W. BIEDEL, F DAYTON, OHIO, ASSIGNOR T0 DELCO-BEMY COBPCRATION, OF DAYTON, OHIO, A CORPORATION OF DELAWARE scum) srenn.

Application filed March 19, 1928. Serial No. 262,727.

This invention relates to sound signals and particularly to horns for automotive vehicles and particularly to the type of horn which comprises a sound chamber enclosed 6 by a diaphragm and a projector and enclosing an auxiliary vibratory plate or disk which is caused to vibrate when the diaphragm is vibrated. The disk is preferably made of such metal that the disk may pro- 10 duce a bell-like tone when maintained in a state of vibration in order that the funda mental tone of the horn provided by the vibrating diaphragm will be modified or colored by the tone of higher pitch produced by the vibratory plate or disk. The disk is preferably attached to the diaphragm at v the region of greatest oscillation thereof and the disk is preferably of such size that it may operate effectively as a piston which transmits to the column of air in the projector the movement which takes place at the center of the diaphragm. Aside from these functions the vibratory disk operated to weight or load the diaphragm so as to decrease its frequency so that the fundamental tone of a lower pitch will be produced.

Theproblem of providing a vibratory disk which will perform the functions which have been mentioned is not easily solved in all cases since it is apparent that a disk having the necessary weight for properly loading the diaphragm and having the necessary di-' ameter to operate effectively as a piston, may

335 not have a natural frequency which is desirable for the purpose of producing a tone of desired high pitch. I am aware that in the' copending application of Robert M. Critchfield, Serial No. 221,473, filed Septemher 23, 1927, there is disclosed a. resonator disk made of sheet metal and the fact that the natural frequency of the disk can be varied according to the extent to which the disk is placed under strains during the 0peration of forming or drawing the disk from a blank of flat sheet metal. My present justment the tone of the horn can be modified within certain limits without disassembling the horn and even while the horn is maintained in operation.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of embodimentof the present invention is clearly shown.

In the drawings:

Fig. 1 is a longitudinal sectional view of the horn embodying the present invention.

Figs. 2 and 3 are fragmentary cross sectional views taken on the lines 22 and 33 of Fig. 1. P

The tone chamber of the horn is enclosed by a vibratory diaphragm 20, a projector 21 and a projector collar 22 which supports the projector in spaced relation to the diaphragm 20. The edge of the diaphragm 20 is clamped by screws 23 and nuts 24 between the flange 25 of the collar 22 and a flange 26 of the frame 7 of the electromagnetic motor which operates the diaphragm.

The actuating motor comprises an electromagnet. including a coil 30 which surrounds a core 31 attached to amagnet frame 32 of U-sha e formation shown in. detail in the copen ing application of Robert M. Critchfield, Serial No. 184,507, filed April 18, 1927. The frame 32 and the frame 27 are composed of magnetizable metals, and. likewise the movable armature 33, which is attracted toward the core 31 when the magnet is energized and which recedes from the core when the ma net circuit is interrupted, owing to the resi iency of the diaphragm 20 to which the armature 33 is attached. As the armature 33 approaches the core 31 its flange 34 engages a non-conducting flexible strip 35 and causes the latter to push a conducting flexible strip 36 toward the left in order to separate a contact 37 attached to the strip 36 from a contact 38 attached to a terminal bracket 39. As the circuit interrupter is not er se a part of the present invention and has been described in the Critchfield ap lication referred to, a detailed description 0 the circuit interrupter is not necessary. Let it suffice to say that the contacts 37 and 38 are in series with the electro-magnet winding 30 so that when this winding is connected with a suitable source of current the armature will be intermittently attracted and intermittently permitted to recede from the core in order to maintain the diaphragm 20 in a state of vibration.

The diaphragm 20 is provided with a central hole which is flat on one side and which receives the similarly formed shank 40 of a nut 41, said shank passing also through a fiat washer 42. The end portion of the shank 40 which passes through the diaphragm 20 is provided with radially extending notches or serrations cooperating with similarly formed and arranged serrations 43 provided by a fulcram block 44 having on one side thereof an annular head 45 hearing against the diaphragm 20. and on the right side thereof as viewed in Fig. 1, an annular head 46 for a purpose to be described. The shank 47 of the armature 33 passes screw threadedly through the nut 41 and through a central opening in the block 44 and a central opening in a vibratory plate or disk 48, and is threadedly engaged by nuts 49 and 50 having a lock washer 51 between them. The vi bratory disk 48 is formed preferably from a blank of flat sheet metal capable of producing a ringing bell-like tone when vibrated. In order to vary the pitch of the tone produced by the vibratory disc 48 it is clamped between the nut 49 and the fulcrum block 44 under varying degrees of stress. I may vary the pitch of the tone produced by the disk 48 by screwing the nut 49 along the shank 47 of the armature 33. I may turn this nut 49 by means of a socket wrench having a long shank which may extend through the projector 21 and which is sufliciently large to straddle the nut 50. If I thread the nut 49 along the shank 47 of the armature 33 toward the disk 44, I will increase the stress in the disk 48 and thereby increase its natural frequency, and, vice versa, decrease the flQ-. queney if the nut 49 is screwed away from the plate 44. After having located the nut 49 in the proper position, it may be locked in this position by tightening the nut 50.

It is apparent that the tightening of the nut 49 tends to turn the shank 47 of the armaturc 33, but I prevent such an occurrence by mechanically connecting the shank 47 with the diaphragm 20 by disconncctihle mechanical means which will permit the adjustment of the shank 47 relative to the diaphragm so that the air gap between the armature 33 and the core 31 may be varied. This mechanical connecting means comprises a lug or key integral with the block 44 and extending into a keyway or slot 61 provided by the armature shank 47. It is therefore apparent that be forethe disk 48 is assembled, one may use the plate 44 as a convenient means for turning the armature 33 in order to thread it relative to the nut 41. After the air gap between the armature 33 and the core 31 has been properly adjusted, one may prevent the turning of the shank 47 by pushing the block 44 toward the diaphragm 20 so that its serrations 43 may engage similar serrations provided by the nut 41. Since the nut 41 cannot turn relative to the diaphragm 20, it is apparent that the block 44 cannot turn when its serrations are engaged by those of the nut 41. It is also apparent that. after the vibratory disk 48 is assembled. the turning of the nut 49 in order to vary the tone of the disk, will not cause the shank 47 to turn since it is mechanically fastened to the diaphragm 20.

It is therefore apparent that the present invention is conducive to economy in manufacture of horns of this type and provides an easy solution of the problem of constructing a vibratory disk which will have all three of the characteristics referred to, viz: sutlicient weight to load the diaphragm, sufficient diameter so that it may serve as a piston to effectively vibrate the air in the projector and tone chamber, and also the characteristic of producing the tone of desired pitch for coloring the tone of the diaphragm. Since many variables enter into the manufacture of sheet metal disks of this type, it is apparent that although a considerable quantity of disks would be uniform with respect to the first two characteristics, there might be considerable variation in the pitch of these disks. However, the disk can be readily adjusted for required tone by the very simple operation of turning an adjusting nut. it is apparent that the nut 49 may be adjusted without disassembling the horn and also while maintaining the horn in operation.

\Vhile the form of embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other. forms might be adopted all coming within the scope of the claims which follow.

lVhat is claimed is as follows:

1. A sound signal comprising an undulated disc; means or supporting said disc, said means clamping upon one of the undulations of said disc; and means for varying the clamping effort of the supporting means whereby the fibers of the clamped undulations are variably stressed.

2. A sound signal comprising a metallic disc having concentrically arranged undulations; supporting means clamping the central 1 undulations of the disc; and means for varying the clamping effort of the supporting means whereby the periphery of the disc will be extended radially and the peripheral fibers placed under varying tensional stresses.

'3. A sound signal comprising a diaphragm; a nut secured to the diaphragm; an electro-magnetfor vibrating the diaphragm, said electro-magnet having an armature interposed between the diaphragm and electromagnet a screw-threaded shank onsaid armature threadedly engaging and extending through the nut on the diaphragm; a fulcrum block attached to the shank of the armature and engaging the diaphragm; an un- 2 dulated, resonant plate supported on said shank; and a nut on said shank, engaging the plate, and adjustable to vary the curvature of the undulations of said plate.

4. In a device of the character described,

the combination with a vibratory diaphragm; a screw-threaded shank secured to said diaphragm; a fulcrum block attached to the shank sol-as to engage with the diaphragm; an undulated resonant plate supported by the shank and engaging the fulcrum block; and a nut on said shank, operable to clamp the plate upon the block with varying degrees of pressure whereby the curvature of the undulations of said plate will be varied and the periphery of said plate extended radially so that the fibers thereof will be placed under varying tensional stress.

5. In a device of the character described, the combination with a vibratory diaphragm of a nut axially secured to the diaphragm; a screw-threaded shank carried by the nut and extending from both sides of the diaphragm; a fulcrum block supported on the shank, one side engaging with the diaphragm the other side having an annular bead; an undulated, resonant plate carried on said shank, and a nut on the shank, operable to clamp the plate against the annular-bead of the fulcrum block whereby the curvature of the undulations of the plate will vary in accordance with the pressure exerted by the nut.

6. In a device of the character described, the combination with an apertured diaphragm; a nut secured in the aperture of the diaphragm; an armature having a screwthreaded shank extending through the not, said shank having a key-way longitudinally thereof. a fulcrum block slidably fitting upon the said shank, said block having a tongue extending into the key-way of the shank, one side of the block engaging the diaphragm the other side having an annular bead; an undulated, resonant plate supported on the shank; a nut on the shank operable to urge the plate into engagement with the annular bead of the fulcrum block whereby the curvature of the undulations are adapted to be varied by adjustments of said nut; and an electromagnet for operating the armature to cause the diaphragm and resonant plate to vibrate.

7. In a signalling instrument, the combination with a vibratile diaphragm; a curved, resonant disc; and means for securing said disc to the diaphragm and for variably stressing the disc to alter the curvature thereof.

8. In a signalling instrument, the combination with a vibratile diaphragm; a resonant disc having a bowl-shaped central portion; and a clamping member on the diaphragm for securing the disc to thediaphragm and for variably stressing the central bowl-shaped portion of the disc to alter its curvature.

9. In a signalling instrument, the combination with a vibratile diaphragm; a corrugated, resonant disc; and means on the diaphragm for attaching the disc thereto, said means being adapted to subject the disc to different stresses for varying the curvature of its corrugations.

10. In a signalling instrument, the com bination with a vibratile diaphragm; a. resonant plate having a curved central portion; a pressure block carried by the diaphragm; and clamping means adapted to clam the plate upon the block so that the curve portion of the plate engages the edge of the block,

variable pressurcsof said clamping means varying the curvature of said plate.

11. In a signalling instrument, the combination with a vibratile' diaphragm; a resonant plate having a curved central portion; a pressure block carried by the diaphragm, said block having an annular ridge adapted to engage the curved portion of the plate at points spaced from its center; and means adapted to apply variable pressure upon the central portion of the plate to urge the curved portion thereof against the ridge of the block variably to deform the curvature of said plate.

12. In a signalling instrument, the combination with a vibratile diaphragm; a threaded member attached to said diaphragm; a nut screw-threaded on said member; a corrugated, resonant plate supported by said member and engaged by the nut; a ressure block interposed between the diap ragm and plate, said block being adapted to alter the cur-"atures of the corrugations of the plate in response to varying pressures of the nut upon the plate.

13. In a signalling instrument, the combination with a vihratile diaphragm; a screwthreaded stud secured centrally of said diaphragm; a. fulcrum block on said stud, one side engaging the diaphragm, the other side 5 having extending portions spaced equally from the axis of the stud; a resonant disc having a bowl-shaped central portion, apertured' to fit upon the stud; and an adjustable clamping nut on the stud adapted to urge the disc in against the extending portions of the fulorum block, variable pressures of the nut upon the disc altering the curvature of the bowl-shaped center of the disc to change its resonance.

3 In testimony whereof I hereto afiix my signature.

WALTER W. RIEDEL. 

